Color photography



June 15, 1943. E. E. JELLEY EI'AL 2,322,027

COLOR PHOTOGRAPHY Filed Dec. 26, 1940 MATER/AL LOW-BOILING /6./

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f/JMNEJELLEY PAUL M V/Tn/M INVENTORS A TTORNE Y Patented June 15, 1943COLOR PHOTOGRAPHY Edwin E. Jelley and Paul W. Vlttum, Rochester, N. Y.,assignors to Eastman Kodak Company,

Rochester, N. Y., a corporation of New Jersey Application December 26,1940, Serial No. 371,612 In Great Britain February 24, 1940 13 Claims.

This invention relates to color photography and particularly to a methodfor incorporating couplers'in silver halide emulsion layers.

The incorporation in silver halide emulsion layers of compounds whichare capable of combining with the oxidation product of developin agentsto produce dye images has been proposed many times. In 1913 RudolfFischer suggested a p ocess of three-color photography which involvedthe incorporation of couplers or color forming compounds in threedifferentially colorsensitized emulsion layers, each coupler capable ofproducing a color complementary to the sensitivity of the layer in whichit was incorporated (Fischer U. S. Patent 1,055,155, March 4, 1913). Thecouplers suggested were compounds containing phenolic hydroxyl or acidmethylene groups which were capable of reacting with the developmentproduct of aromatic amino developing agents on photographic developmentto form dyes of the indophenol, indoaniline and azomethine classes.While the Fischer process was theoretically feasible, it did not achievesuccessful results because, among other reasons, of the tendency of thecouplers to wander from the emulsions in which they were incorporatedeither during coating or during processing. More recent patents haveproposed the reaction of coupler molecules with high molecular orcolloidal bodies so that the coupling properties of the coupler are notdestroyed but the coupler is rendered nondiflusing in gelatin or othercolloidal media, These proposals involve additional steps in thepreparation of the emulsion and it is sometimes difficult to secure aproduct which has the desired coupling properties and which may beincorporated in the emulsion in a satisfactory manner.

A still different method of incorporating couplers in emulsion layershas been proposed in Martinez U. S. Patent 2,269,158, granted January 6,1942, and in Mannes & Godowsky U. S. applications Serial Nos. 314,688and 314,689, filed January 19, 1940. According to the methods of theseapplications, the coupler is mixed with a waterinsoluble colloid such asa natural or synthetic resin or a cellulose ester and the mixture of thecoupler and the Water-insoluble colloid is dispersed in a gelatinemulsion. One of the advantages of these methods is that it isfrequently unnecessary to increase the molecular weight of the couplerappreciably in order to prevent diffusion of the coupler in theemulsion. The existence of an interface between the materials in whichthe coupler is incorporated, that is, the water-insoluble celluloseesters or resins, and the gelatin of the emulsion, prevents wandering ofthe coupler. A further advantage of this method is that the couplers maybe incorporated in their neutral form, that is, it is not necessary toform the sodium salt of the coupler as in the case of previous methods.The colloidal materials with which the couplers are mixed in theseprocesses are usually solids at room temperature and, in order toincorporate the mixture in an emulsion, it is necessary to dissolve itin a volatile solvent for both the coupler and the colloidal materialand to incorporate the solution in the emulsion after which the volatilesolvent is removed, either in a separate step or in the natural processof drying the coated emulsion layer.

In processes of the latter type, difiiculties arise in some cases due tothe solid nature of the final particles in which the couplers areincorporated. One of these difficulties is due to the limited solventaction which the solld colloid material has for the coupler and the dyederived from it, which increases the tendency for the coupler or dye, orboth, to separate as a crystalline deposit on aging of the finishedemulsion coatings. Furthermore, it is in some cases difllcult to find acolloid material having the necessary solvent action for the couplerwhich is also sufficiently permeable to the processing solutions.

It is, therefore, an object of the present invention to provide a novelmethod for incorporating couplers in gelatin emulsions. A further objectis to provide a method of improving the transmission characteristics ofthe image dyes produced by coupling. A still further object is toprovide a method for rendering the particles containing the couplersmore readily permeable by the photographic processing baths. Otherobjects will appear from the following description of our invention.

These objects are accomplished by forming a liquid solutionof thecoupler and a high-boiling water-insoluble crystalloidal material andemulsilying or dispersing the mixture in a photographic emulsion.

In the accompanying drawing, Fig. 1 is a diagrammatic illustration ofthe steps in our process and Fig. 2 is an enlarged sectional view of afilm made according to our invention.

According to the present invention, there is provided a sensitivephotographic silver halide emulsion having a water-soluble binder suchas material bein so chosen that the particles are liquid under theconditions of coating and processing the emulsion. We have found thatcouplers which are solids under ordinary conditions can be convertedinto liquids of oil consistency by the addition of certain high-boilingorganic compounds which are insoluble or only very slightly soluble inwater and in the liquid photographic emulsion. There is little or notendency for crystallization to occur even when the coupler is presentin a proportion amounting to 50% or more of the high-boilingcrystalloidal material.

The invention, therefore, includes a sensitive photographic silverhalide emulsion having a water-soluble binder such as gelatin in whichare dispersed particles of oil-like consistency composed of coupler anda high-boiling waterinsoluble crystalloidal organic compound. Incarrying out the invention, the coupler which has been mixed with thehigh-boiling organic compound to produce an oil-like mixture may bedispersed in water or gelatin solution or in any aqueous binder ofcolloidal character which is miscible with the silver halide emulsion.The dispersion may be afiected with the aid of homogenizer, colloid millor the like and the dispersions may be stabilized by the addition ofemulsifying agents such as those of the well known higher fatty alcoholsulfate type. The

dispersion may also be formed by dispersing a v solution of coupler, andcrystalloidal material, in a solvent of low boiling point such as butylacetate, with water or gelatin solution and subsequently removing thelow boiling solvent by evaporation. Here also an emulsifying agent maybe used.

In our process it is important that the mixture of coupler andcrystalloidal material be a liquid at ordinary temperatures. This formsliquid particles when the mixture of coupler and crystalloidal materialis emulsified in water and mixed with a gelatin emulsion, theseparticles retaining the coupler in solution, yet being readilypenetrated by the photographic developing solution and other processingbaths.

In ,our process we prefer to use the customary gelatino-silver halideemulsions although other water-soluble colloidal materials can be usedfor the photographic emulsion such as agar or watersoluble syntheticresins. The emulsions may be used in single layer or in multi-layercoatings and our invention is especially designed for the production ofmulti-layer coatings for natural color photography.

We have referred to the high-boiling crystalloidal materials with whichthe couplers are mixed. Since this constitutes a distinguishing featureof our invention, this material will now be fully described.

The high-boiling crystalloidal materials which .we contemplate usinghave been referred to as oil formers" because they have the property ofproducing an oily or liquid solution when mixed with the coupler eventhough the coupler is a solid. The compounds are generally liquid atordinary temperatures or low melting solids (below 100 0.). that ingeneral the most useful compounds contain one or more polar groups suchas halogen, hydroxyl, carboxylic acid, amide, ketone, etc.. althoughthis is not a limiting factor. They should have a high solvent actionfor the coupler and for the dye produced by coupling and should, ofcourse be inert toward the silver halide emulsion in which they areincorporated. Th y It has been found also' should also be substantiallycolorless and stable toward light, heat and moisture, in addition tobeing inert to the various processing baths which may be encounteredsuch as developers, oxidized developers, silver removal baths and fixingbaths. They should be of low volatility and in general we have foundthat compounds suitable for this purpose have boiling points above or C.at atmospheric pressure. They should be permeable to photographicprocessing solutions since this affects the ease of dye formation andthe removal of excess developer, the latter in turn affecting theformation of stain. They should have a sufiiciently low refractive indexso that the solutions of couplers in them have approximately the samerefractive index as gelatin. thereby minimizing the opacity or lightscattering of the coating. Most couplers themselves have high refractiveindices and for this reason it is desirable that the oil formers havelow refractive indices. They should be easily dispersible in emulsionsand should be chemically inert toward the couplers and dyes formed fromthem.

It is sometimes advantageous to employ a mixture of two or moreindividual crystalloidal materials or oil formers in the same dispersionin order to obtain the desired combination of properties. Thus one mightuse a mixture of one compound having exceptionally good solvent action,with another compound added in the correct proportions to give the finaldispersion the desired refractive index.

It might be of advantage also to use oil formers which could be removedfrom the coated emulsion layer or layers at any desired stage of theprocess. This could be accomplished, for example. with some of theacidic oil formers which would be removed from the coating in analkaline bath. An oil former might also be chosen which was incapable ofdifi'using through gelatin but which could be changed chemically before,during or after the processing steps into a substance or substanceswhich would be removable.

The following high boiling crystalloidal materials or oil formers havebeen found suitable for use in our invention, this list beingillustrative only.

Acids p-Sec. amylbenzoic acid fi-Phenylpropionic acid Dibenzyl aceticacid Phenyl ethyl acetic acid Mono-n-amylphthalate (acid ester)Undecylenic acid Benzyl hydrogen succinate (acid ester) Alcoholsn-Hexylphenylcarbinol p-(p-Tert. butyl phenoxy) -ethyl alcohol AmidesAcetyl n-butyl aniline Acetyl methyl p-toluidine Benzoyl piperidineAmide derivatives Carbamates Ethyl N,N-di-n-butyl carbamate EthylN-phenyl carbamate Esters Ketone derivatives Benzophenone2,4-dichlorobenzophenone a-Methoxy acetophenone Acetophenone2,4-dihydroxy valerophenone p-Sec.-amylbenzophenone Phenol ethersVeratrole (1,2-dimethoxybenzene) Eugenol methyl ether Hydroquinonedimethyl ether Phosphate esters Triphenyl phosphate Tricresyl phosphateDiphenyl mono-p-tert. butyl phenyl phosphate Monophenyl di-p-tert. butylphenyl phosphate Diphenyl mono-o-chlorophenyl phosphate Monophenyldi-o-chlorophenyl phosphate Tri-p-tert. butyl phenyl phosphateTri-o-phenylphenyl phosphate Di-p-tert. butyl phenyl mono (-tert.butyl-2- phenylphenyl) phosphate Sulfonamides p-Toluenesulfonyl methylo-toluidine p-Toluenesulfonyl dimethylamide Sulfonamides derivativesp,p'-Di-n-amylbenzenesulfonanilide p-Toluenesulfonyl di-n-butyl amideSulfones n-Butyl sulfone Iso-amyl sulfone Ureas N,N'-diethyl-N,N'-diphenyl urea N,N-di-n-butyl urea In addition to thesecompounds there are other compounds suitable with respect to physicalproperties but unsuitable for other reasons. In some cases thesecompounds can be used in admixture with other compounds. For example, ithas been found that nitrobenzene, o-nitrotoluene, 2-nitro-p-eymene ando-nitro-diphenyletherwhich are good oil formers,'unfortunately have adesensitizing action but by mixing the nitro compound with anothermaterial, for example, by mixing o-nitrodiphenylether withtrio-eresylphosphate in amounts up to 25% there is no seriousdesensitization of the emulsion. Similarly, crystallization of anotherwise suitable combination of oil formers and couplers may often beprevented by using a mixture of closely related but non-isomorphouscouplers.

We have referred to dissolving the coupler and the high boiling solventin low boiling solvent and dispersing the mixture in an aqueous solutionafter which the lower boiling solvent is removed. Although this is notnecessary in our process, in many cases it is desirable to proceed inthis Way using a solvent which can be removed before coating theemulsion. Low boiling solvents suitable for our purposes includenitromethane, nitroethane, methyl, ethyl, propyl and butyl acetates andethyl and butyl formate.

In dispersing the mixture of coupler and high boiling solvent in theaqueous solvent, it is desirable to use an emulsifying agent such asGardinol a higher fatty alcohol sulfate) or Arctic Syntex T (U. S.Patent 1,932,180). Gelatin may also be used as an emulsifying agent orthe mixture of coupler and high boiling solvent may be disperseddirectly in the photographic emulsions. The coupler suitable forincorporation in emulsions according to our invention will be understoodto be the customary type containing phenolic hydroxyl or reactivemethylene groups. The following may be used.

Couplers producing cyan images rmmylphenoxyhon'wnenulfnnnmlno) -lmaphthol -(N-benzyl-N-nnphihalem-sulfonamino) -1-naphlhol-(n-benzyl-N-n-vulorylamino) -i mlphthol ma nroylnm nwl nn ph thol-ctlilolro-5-(N-n-valeryl-Nplsopropylbenzylaminn) l-nnnh Couplersproducing magenta images nmylsullani- Couplers producing yellow imagesIn order more clearly to explain our invention, reference will now behad to the accompanying drawing. As shown in Fig. 1, which is adiagrammatic illustration of our process, a mixing vessel I is used toproduce an intimate mixture of the coupler and the high boilingcrystalloidal material added to it. A suitable stirring device 2 may beattached to the tank and a low boiling solvent may be added through thepipe 3. After admixture of these materials in the tank I, watercontaining an emulsifying agent may be added through the pipe 4 and themixing continued. The mixture is then passed through pipe 5 to thecolloid mill or homogenizer 6 in which a dispersion of the coupler; highboiling crystalloidal material and low boiling solvent in water isproduced. After homogenization, the dispersion is passed through pipe 1to steam bath 8 which is heated by suitable means not shown and wherethe low boiling solvent is removed. Some of the water may also beremoved at this stage leaving a dispersion of the coupler and highboiling material in an aqueous solution. This dispersion is passedthrough pipe 9 into container 80 where a gelatino silver halide emulsionis added through pipe II. The dispersion of coupler and high boilingmaterial in water is mixed with the silver halide emulsion by means ofany suitable device such as the stirrer l2 and the resulting emulsion ispassed through pipe l3 to the coating hopper M where it is coated as alayer IS on the film base 16 passing beneath the coating outlet of thehopper l4.

Successive emulsion layers may be coated on the support in a similarmanner after the first coated emulsion layer is dried or partially driedin the well known manner. The resulting film in sectional view is shownin Fig. 2-in which I1 is a support of suitable material such ascellulose ester, synthetic resin, metal or paper, coated with emulsionlayers l8, l9 and 20 containing, respectively, red-sensitive silverhalide grains 2!, green-sensitive silver halide grains 22andbluesensitive silver halide grains 23. Emulsion layer l8 containsparticles 24 of cyan coupler and crystalloidal material, emulsion layerI9 contains particles 25 of magenta coupler and crystalloidal materialand emulsion layer 20 contains particles 26 of yellow coupler andcrystalloidal material. The film also contains the usual yellow filterlayer 21 between the green-sensitive emulsion layer 19 and theblue-sensitive emulsion layer 20. It is to be understood that by cyancoupler, magenta coupler and yellow coupler we mean that the dyesproduced by these couplers on development are cyan, magenta and yellowand not that the couplers are these colors prior to development.

The following examples, which are illustrative only, indicate methods offorming dispersions of coupler and crystalloidal materials according toour invention:

Example 1 A solution of 7.5 grams of 2-lauryl-4-chlorophenol in grams ofveratrole (1,2-dlmethoxybenzene) was added to 200 cc. of water contain2.0 grams of the wetting agent, Gardinol WA. The whole mixture wasstirred to effect preliminary emulsification, then passed through acolloid mill several times while the temperature of the solution and themill was maintained at about C. In this way, a very stable and very fineemulsion was obtained which was added to 1000 cc. of a. melted silverhalide gelatin emulsion.

The emulsion containing the added coupler dispersion was coated on asuitable support, set and dried in the usual manner. On development ofthis emulsion with a developing solution employing 2-aminofi-diethylaminotoluene as the developing agent and subsequent removal ofsilver, a cyan dye image was obtained.

Example 2 Five grams of the cyan coupler. 5-(N-benzyl-N-naphthalene-sulfonamino)-1-naphthol, were dissolved in a mixture of 15grams ethyl acetate and 15 grams of ethyl N,N-di-n-butyl carbamate. Tothis solution was added a solution of 2 grams tri-isopropyl-naphthalenesulfonate and 0.2 gram glyceryl monostearate in 250 cc. of water.Emulsification was effected in the same manner as in Example 1, and theresulting emulsion added to 1000 cc. of melted silver halide gelatinemulsion. On development as described in Example 1, a cyan dye image wasobtained.

Example 3 A solution was prepared by gentle warming of 5 grams of1-p-phenoxyphenyl-3-amyl-fi-pyrazolone, 12.5 grams dimethylphthalate,and 20 cc. n-butylacetate. This solution was heated to F. and then addedto 750 cc. of a melted silver halide gelatin emulsion, also at 95F.Preliminary emulsification was efiected by vigorous stirring, then thewhole mixture passed through a colloid mill, the grinding chamber ofwhich was maintained at 95 F. by means of water at this temperaturecirculated through the jacket. The emulsion containing the dispersedcoupler and solvent was then coated, set and dried. On development aspreviously described, a magenta dye image resulted.

Example 4 A solution was prepared containing 15 grams of methylo-methoxy benzoate, 65 grams butyl acetate, 35 grams of ethyl acetate,and 5 grams of the magenta coupler 2-cyanoacetylcoumarone 5-(N-n-amyl-p-tert. amylsulfanilide) This solution was emulsified bypassage through a homogenizer with 450 cc. of water containing 2.5 gramsof Gardinol WA. The resulting dispersion was heated to C. on a steambath with constant stirring and with a stream of air blowing over thesurface of the solution until all of the ethyl and butyl acetates hadbeen evaporated from the mixture. At this stage, the volume of thesolution was about 200 cc. This was added to 1000 cc. of silver halideemulsion and further treated as described above. The material yields amagenta image.

Example 5 Ten grams of the yellow coupler,n-propyl-pbenzoylacetamino-benzenesulfonate, was dissolved in 25 gramsof methyl-p-toluenesulfonate. This solution was shaken with cc. of a 2per cent solution of gelatin at a temperature of 50 F. The whole waspassed through a'colloid mill, and the resultant dispersion added to1000 cc. of a melted silver halide gelatin emulsion. After coating,drying, and developing as described above, a yellow imagewas obtained.

Example 6 A solution was prepared from 25 grams ethyl benzylmalonate, 45cc. ethylacetate, and 8 grams of the yellow coupler,N-(4-benzoylacetaminobenzenesulfonyl) -N-benzyl-m-toluidine. This wasemulsified with 200 cc. oi water containing 2 grams of Gardinol WA,exactly as described in Example 1. A yellow image is obtained.

Example 7 A dispersion consisting of 1 gram of l-hydroxy- 2-(N-isoamylN-phenyl) -naphthamide dissolved in 3 grams of tri-o-cresylphosphate ina total volume of 50 cc. of water was added to 95 cc. of a polyvinylalcohol silver halide emulsion prepared as described in Lowe U. S.Patent 2,286,215, granted June 16, 1942. After running through acolloidal mill the emulsion containing tri-ocresylphosphate and itsdissolved coupler was coated. This coating produces a cyan dye uponphotographic development.

A similar coating was made containing a dispersion oi 0.5 gram of1-p-laurylphenyl-3- methyl-5-pyrazolone dissolved in 2.5 grams oftri-o-cresylphosphate dispersed in 50 cc. of water. The dispersion oftri-o-cresyl phosphate containing the coupler was added to 80 cc. of apolyvinyl alcohol emulsion similar to that described above and, afterhomogenizing in a colloid mill, the emulsion containing the couplerdispersed in tri-o-cresyl phosphate was coated. The coupler produced amagenta dye upon exposure and development. Plates from the twopreparations after drying were exposed to white light and de veloped inthe following solution:

2-amino-5-diethylamino toluene HCl grams-.. 2 Sodium sulfite do 2 Sodiumcarbonate do 20 Potassium bromide do 2 Water to cc 1000 Cyan and magentadyes were obtained in the portions of the plates which were exposed tolight, the corresponding dye being produced in its respective coating.

In addition to the advantages which will be apparent from the foregoingdescription of our invention, we have also discovered the surprisingfact that a number of the high-boiling crystalloidal materials possessthe valuable property of causing a shift in the absorption of the dyesformed during color development. For example the dye from a magentacoupler of the cyanoacetylcoumarone type dispersed in tri-o-cresylphosphate has its maximum absorption at 540 millimiorons. The same dyein a-naphtholacetate has its maximum absorption between 547 and 548millimiorons. Similar shift in absorption is obtained with othercouplers such as yellow and magenta couplers of thecyanoacetylnaphthalene and pyrazolone series. Crystalloidal materialsexhibiting this behavior include acetyl-N-butylaniline,acetylmethyl-p-toluidine, methylphthalate, butyl-o-methoxybenzoate, 1,2-dimethoxyben'zene, N,N'-diethyl-N,N'-diphenyl urea andethyl-N,N-di-n-butylcarbamate. In addition, many of the dyes produced inthis way have better absorption characteristics than similar dyesdispersed in gelatin without the oil formers.

It is to be understood that the modifications and examples included inthe present specification are illustrative only and that our inventionis to be taken as limited only by the scope of the appended claims.

We claim:

1. The method of incorporating a color-former in a water-solublesensitive photographic colloid which comprises mixing a color-formingcompound capable of reacting with a primary aromatic amino couplingdeveloping agent on photographic development, with'a substantiallywaterinsoluble, low molecular weight, organic, crystalloidal materialhaving a boiling point above about 175 C., said organic material havinga high solvent action for thecolor-forming compound and for the dyesformed therefrom, and being permeableto photographic processingsolutions, the nature and proportions of the colorforming compound andcrystalloidal material being so chosen that particles thereof are liquidunder conditions of coating and processing the sensitive photographiccolloid, said mixture being a liquid solution of said color formingcompound and said crystalloidal material, and dispersing said solutionin the sensitive photographic colloid to form liquid, particles 01 thecolor-forming compound and crystalloidal material in dispersed form inthe photographic colloid.

2. The method of incorporating a color-former in a gelatino-silverhalide emulsion which comprises mixing a color-forming compound capableof reacting with a primary aromatic amino coupling developing agent onphotographic development, with a substantially water-insoluble, lowmolecular weight, organic, crystalloidal material having a boiling pointabove about C., said organic material having a high solvent action forthe color-forming compound and for the dyes formed therefrom, and beingpermeable to photographic processing solutions, the nature andproportions of the color-forming compound and crystalloidal materialbeing so chosen that particles thereof are liquid under conditions ofcoating and processing the emulsion, said mixture being a liquidsolution of said color-forming compound and said crystalloidal material,and dispersing said solution in the gelatino-silver halide emulsion toform liquid particles of the colorforming compound and crystalloidalmaterial in dispersed form in the emulsion.

3. The method of incorporating a color former in a gelatino-silverhalide emulsion which comprisesmixing a color-forming compound capableof reacting with a primary aromatic amino coupling developing agent onphotographic development, with a low boiling water-insoluble organicsolvent for the color-forming compound and a substantially waterinsoluble, low molecular weight, organic, crystalloidal material havinga boiling point above about 175 C., said organic material having a highsolventaction for the color-forming compound and for the dyes formedtherefrom, and being permeable to photographic processing solutions, thenature and proportions of the color-forming compound and crystalloidalmaterial being so chosen that particles thereof are liquid underconditions of coating and processing the emulsion, said mixture being aliquid solution of said color-forming compound and said crystalloidalmaterial, dispersing the mixture in water, removing the low boilingsolvent and dispersing said solution in the gelatino-silver halideemulsion to form liquid particles of the color-forming compound andcrystalloidal material in dispersed form in the'emulsion.

4. The process of claim 3, in which the crystalloidal material is atriaryl ester of phosphoric acid.

5. The process of claim 3, in which the crystalloidal material is atriaryl ester of phosphoric acid and the low-boiling solvent is an esterof a lower fatty acid and a lower fatty alcohol.

6. The process of claim 3, in which the crystalloidal material intricresyl phosphate and the low-boiling solvent is butyl acetate.

7. The process of claim 3, in which the crystalloldalmaterial is methylphthalate and the low-boiling solvent is butyl acetate.

8. The process of claim 3 in which the crystalloidal material isdibutylphthalate and the low-boiling solvent is ethyl acetate.

9. A light-sensitive emulsion for producing a colored image comprisingfinely divided liquid particles of a mixture of color former and asubstantially water-insoluble, low molecular weight, organic,crystalloidal material having a boiling point above about 175 C., saidcrystalloidal material having a high solvent action for the color formerand for the dye formed therefrom, and being permeable to photographicprocessing solutions, the nature and proportions of the color former andcrystalloidal material being so chosen that particles thereof are liquidunder conditions of coating and processing the emulsion, said particlesbeing dispersed in a gelatino-silver halide emulsion.

10. A multi-layer photographic element comprising at least onegelatino-silver halide emulsion containing finely divided liquidparticles of a mixture of color former and a substantiallywater-insoluble, low molecular weight, organic, crystalloidal materialhaving a boiling point above about 175 C. said crystalloidal materialhaving a high solvent action for the color former and for the dye formedtherefrom and being permeable to photographic processing solutions, thenature and proportions of the color former and crystalloidal materialbeingso chosen that particles thereof are liquid under conditions ofcoating and processing the emulsion, said particles being dispersed inthe emulsion.

11. In the method of incorporating a coupler in a gelatlno-silver halideemulsion layer, the

steps which comprise forming a liquid mixture of the coupler and acrystalloidal material having a boiling point above about 175 C., thenature and proportions of the coupler and crystalloidal material beingso chosen that particles thereof are liquid under conditions of coatingand processing the emulsion, and dispersing said mixture as finelydivided liquid particles permeable to photographic processing solutionsin said emulsion.

12. In the method of incorporating a coupler in a gelatino silver halideemulsion layer, the steps which comprise forming a. liquid mixture ofthe coupler and a triaryl ester of phosphoric acid and dispersing saidmixture as finely divided liquid particles in said emulsion.

13. In the method of incorporating a coupler in a gelatino-silver halideemulsion layer, the steps which comprise forming a liquid mixture of thecoupler and tricresyl phosphate and dispersing said mixture asfinely-divided liquid particles in said emulsion.

EDWIN E. JELLEY. PAUL W. VITTUM.

